Magnetic signal



Patented Jan. 16, 1945 MAGNETIC SIGNAL Ernest S. McLarn, Manhassct, N. Y., and Frank A. Leibe, Quakertwn,'Pa., assignors to International Standard Electric Corporation, New York, N. Y., a corporation of Delaware Application March 10,1942, Serial No. 434,134

Claims.

This invention relates to new and useful improvements in magnetic signals and particularly to signals operated by very small currents.

In such signal devices it has been customary to restore the signal to normal after operation by means of a spring member. This member is required to be so delicate however that it becomes a source of trouble due to corrosion, breakage or displacement. The object of the invention is to provide a signal which is held in and returned to the normal position by a permanent magnet instead of a spring, and may be rotated into an actuated position by an electromagnet, the device being so compact that it may be used in a telephone set as a busy signal.

The preferred embodiment of the invention is illustrated in the drawing in which Fig. 1 is a top plan view with parts removed and broken away, Fig. 2 is a vertical cross section partly in elevation, and Fig. 3 is a top plan view of the cover for the device. 7

Referring now to the drawing, I and 2 are pole pieces of an electromagnet the coil of which is illustrated at 3. 4 is a horizontal platform above the magnet coil 3 having turned-up flanges 5 parallel with and fastened to the pole pieces I and 2 by means of screws 8, the pole pieces I and 2 projecting upwardly through suitably formed openings in horizontal platform 4,

A permanent magnet formed of a thin flat strip and having a wide bottom 6 and turned-up vertical pole pieces I is fastened to a tong 9 of the platform 4. The positioning of the permanent magnet on the tong 9 is insured by a protuberance III in the bottom of the magnet engaging within a notch 'II of the tong 9. The permanent magnet is placed at an angle of approximately 45 to a line drawn transversely to the faces of pole pieces I and 2 and extending through the centers thereof with which the central point of the bottom 6 of the permanent magnet is in alignment.

A brass stud I2 fastened to the platform 4 and projecting through a central perforation in the flat bottom 6 of the permanent magnet has an axial perforation within which projects a pivot pin I3 carrying an armature I4 formed out of a flat strip of metal. The shape of the armature I4 is substantially like that of the permanent magnet but it is slightly longer and has legs I5 which hang down over the pole pieces I to a point slightly above the platform 4. The pole pieces 1 and the armature legs I5 are curved on a radius and normally the permanent magnet will attract the armature so as to hold it parallel with itself, i. e., with the legs I5 of the armature overlapping the pole pieces I of the permanent magnet.

When the electromagnet is energized its pole pieces I and 2 will attract the legs I5 of the armature and cause the armature to rotate in a horizontal plane into a position transverse to the faces of the pole pieces I and 2 as shown in Fig. 2; The armature will remain in this position until the magnet coil 3 becomes de-energized whereupon the permanent magnet will attract the armature into its normal, parallel position. Pins 22 and 23 mounted on the platform 4 restrict the movement of the armature in its two directions of rotation so that it cannot overthrow in either direction.

The armature carries, attached to its upper face, a target I6 having alternate white and black markings which are visible through windows II of a cap I8 held within housing I9. The housing fits on top of the up-turned edges 5 of the platform 4. The black markings will appear or disappear from the Windows I! depending upon the position of the armature and thus give an indication.

Connections with the magnet coil 3 may be established by means of terminals 20 mounted in a strip 2| of insulating material fastened to the ends of the up-turned edges 5 of the platform 4.

What is claimed is:

1. A signalling device comprising an electromagnet, a pole-piece, having upwardly extending arms and being formed approximately U- shaped, for said magnet, a non-magnetic pivot support mounted between the arms of said polepiece sustantially parallel thereto, an armature comprising a strip of magnetic material pivoted to said support. said armature being formed in a general U-shape with arms disposed within those of the polepiece but extending in the opposite direction thereto whereby said armature is free to turn within the arms of said polepiece, a pair of stop pins disposed in spaced relationship in the path of said armature for limiting the rotary movement thereof, said electro-magnet when energized being adapted to hold said armature against one of said stop pins, means comprising a permanent magnet for moving said armature and holding it in engagement with the other of said stop pins while said electro-magnet is deenergized, and signal means carried by said armature.

2. A signalling device according to claim 1 in which said permanent magnet is disposed between the arms of said armature.

3. A signalling device according to claim 1 in which said permanent magnet is disposed between the arms of said armature so that the field thereof is angularly displaced from that produced by said electro-magnet by less than 90.

4. A signalling device according to claim 1 in which said permanent magnet is approximately U-shaped and has two upwardly projecting arms, 10

said permanent magnet being disposed between the arms of said armature so that the arms of the permanent magnet are within the path of those of the armature, the field of said permanent magnet being angularly displaced from that 15 magnet.

produced by the 'electro-magnet.

5. A signalling .device comprising an electroa carried by said armature, a permanent magnet for attracting said armature to a rest position upon de-energization of said electro-magnet and a pair of stop pins located in the rotary path of said armature in such positions as to limit the rotary movement of the armature in the enersized and deenergized conditions of said electro- ERNEST S. MCLARN. FRANK A. LEIBE. 

